Well, first of all, buy the book if you don't have it! You can hardly revise for the novella if you don't have it!
Okay, well, for a start, I'm doing WJEC so the following advice will be based on that exam board's requirements.
For John Steinbeck's Of Mice and Men, there are a number of key things you have to revise:
- How John Steinbeck creates mood and atmosphere in the novel. Think about his writing style, his choice of language and metaphors. He manages to keep the settings rich and vibrant without dipping into Le Carre-esque levels of complexity. His choice of dialogue and his use of environmental description to reflect characters. For example, how he emphasises Crooks' isolation through descriptions of his barn being littered with his belongings. You don't have to go through the entire novel, but you need to have an idea of how he uses language to create his settings, characters, and story.
- You will need to look in depth into every character in the play (not as daunting as it sounds considering there are less than 10.) Crooks, Candy, don't spare any of them. For a really good character response in WJEC, you need to look at how Steinbeck uses a range of narrative techniques, such as description and dialogue, to create each character. Furthermore, you will also need to describe the relations between the characters, like Curley's extreme hatred and resentment of Lennie due to his huge stature. You will also need to look at the wider significance of the characters. For example, look at how Crooks comments upon the treatment of blacks in American society, or how Curley reflects the bullying culture that was so prevelent in the workplace without being noticed.
- You need to remember the basic structure of the novel to the point where you can use examples.
- I almost forgot themes. You will need to be able to identify the key themes of the novel, (in this case I believe it's loneliness, dreams, and prejudice) and explain how Steinbeck develops each of them in depth. Such as how prejudice is explored through Curley's treatment of Lennie, and alot of people's treatment of Crooks. Or how dreams are explored through Lennie, George, and eventually Candy's attraction to the idea of "living offa' the fatta' the lan'".
Yeah, I think that's about it, really. :/ I just gave you a brief outline of the stuff I think you really need to know. You'd probably find it would really help if you could get some revision booklets, as the people who write those can probably explain what you need to know far better than I can.